All 42,000 electrocardiograms taken at the University of Oregon Health Sciences Center from 1969 through 1971 were reviewed; 325 patients (0.77%) had left bundle-branch block (LBBB) or right bundle-branch block (RBBB) with axis deviation (AD). In December 1974, 90% were contacted or found to be dead.
The five-year survival rate (actuarial technique) (mean ± SE) was 45.5 ± 2.9%. It was significantly worse than that of age- and sex-matched "controls." In most patients the cause of death could not be determined. Survival of 164 LBBB patients (40.7 ± 4.1%) at five years was not significantly worse than that of 161 RBBB and AD patients (49.5 ± 4.2%). Those with syncope did no worse in terms of survival than did those without. The five-year survival in coronary artery disease patients was 33.7 ± 4.4%; in those with primary conduction system disease (20% of patients), it was 50.6 ± 6.6%.
It will be necessary to know the causes of death and of syncope in conduction disease patients before it can be determined whether or not pacemakers can prevent either.
(Arch Intern Med 138:30-35, 1978)